The company announced that an internal accident investigation board, working with the U.S. Federal Aviation Administration, determined that the faulty connection led to the premature shutdown of the engine in the Electron’s second stage several minutes after liftoff from New Zealand July 4 (U.S. time.)
The failure of the electrical connection caused a loss of power for many systems, including the electric turbopumps that power the engine. “The engine shut down because of insufficient power supply to the electric pumps,” Peter Beck, chief executive of Rocket Lab, said in a call with reporters.
Rocket Lab said the connection was “intermittently secure” throughout the launch, creating electrical resistance that led to heating and thermal expansion of the electrical component. That ultimately caused a disconnection in the overall electrical system, triggering the shutdown.
The problem had not been seen on any previous Electron flights, which flew 728 of those components. Rocket Lab said the problem wasn’t detected in pre-launch tests, but engineers were able to replicate it in tests of similar components after the accident.
“It’s a really unusual thermal problem,” Beck said. “While it’s kind of sneaky and tricky, when you know about it, it’s quite easy to screen for it and measure.”
The failure did not affect the stage’s instrumentation and telemetry, which was able to continue providing data even after the loss of power to the engine. “Telemetry is always a system where you want a tremendous amount of redundancy on,” he said. “The very last system you ever want to go down is your telemetry system, so we have multiple redundancies on that.”
Beck said there are no plans to make major design changes to the rocket, such as increasing redundancy to that electrical system. “The actual system that this is associated with is really robust,” he said. “It really doesn’t warrant a design change. It’s not a fundamental flaw.”
He did say that the company used the failure to look for other changes in procedures it could implement to improve overall reliability. “We took a big step back and a had a look across the whole vehicle, and as a result we’ve made a bunch of changes to work instructions and quality signoffs.”
Rocket Lab plans to resume Electron launches from New Zealand in August. The company did not disclose the payload or the customer for that mission, but Beck said the company will announce that in the near future.
After that return-to-flight mission, Rocket Lab will then perform its first launch from Launch Complex 2 at Wallops Island, Virginia. Beck said he wants to move back to a monthly launch cadence or even more frequently for the rest of the year. That includes an attempt to recover the first stage on a launch later this year.